package org.example.book.config;

import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.SneakyThrows;
import org.example.book.model.Result;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.MethodParameter;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageConverter;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;

@ControllerAdvice
public class ResponseAdvice implements ResponseBodyAdvice<Object> {
    @Autowired
    private ObjectMapper objectMapper;
    @Override
    public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
        return true;
    }

    @SneakyThrows
    @Override
    public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType, Class<? extends HttpMessageConverter<?>> selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
        //在返回之前，需要做的事情
        if (body instanceof Result) {
            return body;
        }
        if (body instanceof String) {
            return objectMapper.writeValueAsString(Result.success(body));
            //将String类型转变为json格式，看似还是字符串，
            // 但是在适配器初始化的时候选择的转换器和转换方法变为了参数为json的
        }
        return Result.success(body);//封装为Result类的success方法中的表达格式，body是Controller中方法返回的结果
    }
}
